Penetration testing is a method of detecting defects on the surface of workpieces by utilizing the permeation effect of liquids on micro pores. Penetrant testing (PT), also known as penetration testing, is a non-destructive testing method based on the principle of capillary action to inspect surface opening defects. This method is one of the five conventional non-destructive testing methods (radiographic testing, ultrasonic testing, magnetic particle testing, penetrant testing, eddy current testing) and is a comprehensive scientific technology.

Like other non-destructive testing methods, penetrant testing is also based on the premise of not damaging the performance of the tested object, using physics, chemistry, materials science, and engineering theories as the foundation to effectively inspect various engineering materials, components, and products, in order to evaluate their integrity, continuity, and safety reliability. Magnetic particle testing is an important means of achieving quality control, saving raw materials, improving processes, and providing labor productivity in product manufacturing. It is also an indispensable means of equipment maintenance.

Color penetrant testing is widely used in the special equipment and machinery industries. The special equipment industry includes pressure equipment such as boilers, pressure vessels, and pressure pipelines, as well as electromechanical equipment such as elevators, lifting machinery, passenger ropeways, and large amusement facilities. Fluorescent penetration testing is widely used in the defense industry fields such as aviation, aerospace, weapons, ships, and atomic energy.

Penetration testing can be widely used to detect surface opening defects in most non absorbent materials, such as steel, non-ferrous metals, ceramics, and plastics. For complex shaped defects, it can also be comprehensively tested in one go. No additional equipment required, convenient for on-site use.

Basic principles of penetration testing

Penetration testing is essentially the capillary action (or capillary phenomenon) of liquids and the luminescence phenomenon of solid dyes under certain conditions.

The working principle of penetration testing is: after the surface of the workpiece is coated with a penetrant containing fluorescent or colored dyes, under capillary action, after a certain period of time, the penetrant can penetrate into the surface opening defects; Remove excess penetrant from the work surface, dry it, and then apply adsorption medium - imaging agent on the surface of the workpiece; Under capillary action, the imaging agent will attract the penetrant in the defect, that is, the penetrant will infiltrate back into the imaging; Under a certain light source (black or white light), traces of penetrant at the defect site are displayed (yellow green fluorescence or bright red), thereby detecting the morphology and distribution of the defect.

method

Penetration testing method, which involves using a liquid dye on the surface of the test material and keeping it on the surface for a predetermined period of time. The dye can be a colored liquid that can be recognized under normal light, or a yellow/green fluorescent liquid that requires special light to appear.

This liquid dye enters the cracks on the surface opening of the material due to capillary action. Capillary action always occurs during the retention of the dye until excess dye is completely washed away. At this point, a certain imaging agent is applied to the surface of the material being tested, penetrating into the cracks and coloring them, thereby revealing. Qualified testing personnel can analyze the visible traces.

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